proj4js

http://proj4js.org/

Proj4js is a JavaScript library to transform point coordinates from one coordinate system to another, including datum transformations.

projection
Version

https://cdnjs.cloudflare.com/ajax/libs/proj4js/2.3.6/proj4-src.js

https://cdnjs.cloudflare.com/ajax/libs/proj4js/2.3.6/proj4.js